The present invention relates to an apparatus for cooling heat generating members, and, more particularly, to a boiling or dipping type cooling apparatus which is capable of improving the efficiency of cooling heat generating members such as semiconductor devices, which can also be easily assembled.
Since computers must have fast processing speeds, a method has been recently developed in which LSIs (Large Scale Integrated circuits) are mounted at high density. Therefore, the LSIs generate excessively large heating values, and the semiconductor devices, on which the LSIs are mounted at high density, also generate excessively dense heat. Hence, it become more critical that the LSIs are efficiently cooled.
As disclosed in, for example, Japanese Patent Publication No. 3-20070 or Japanese Utility Model Publication No. 3-7960, conventional cooling apparatuses cool the LSIs (Large Scale Integrated circuits) by dipping the LSIs in refrigerant liquid having a low boiling point or by boiling refrigerant liquid by spraying pressurized refrigerant liquid having a low boiling point to the LSIs through nozzles.
The aforesaid conventional cooling apparatus which cools the LSIs (Large Scale Integrated circuits) by causing boiling to take place by dipping them into refrigerant liquid and which has been disclosed in Japanese Patent Publication No. 3-20070 is arranged in such a manner that the deterioration of the performance of cooling the LSIs disposed in the upper portion in the vertical direction is prevented even if the cooling liquid starts boiling and if boiled bubbles are generated with the rise of the operation temperature of the LSIs, the deterioration being prevented by allowing the boiled bubbles to disappear by the action of a cooling heat exchanging pipe located in the refrigerant liquid. However, the convection currents generated in the refrigerant liquid due to dipping and boiling is unsatisfactory because the cooling heat exchanging pipe is simply dipped in the refrigerant liquid having a low boiling point. Since the temperature of the refrigerant liquid depends upon the pressure in the refrigerant liquid container, it is difficult to cause the boiled bubbles to efficiently disappear. What is worse, the performance of cooling the LSIs is unsatisfactory because the refrigerant liquid has poor cooling performance. In addition, in the dipping and boiling cooling method, the temperature of the LSI rapidly rises after it has started generating heat until the refrigerant liquid starts boiling. Therefore, the temperature of the LSI rises to a level considerably higher than the designed final temperature if boiling is not smoothly commenced and, as a result, unsatisfactory reliability of the LSI arises.
Accordingly, the cooling apparatus disclosed in Japanese Utility Model Publication No. 3-7960 is arranged in such a manner that the pressurized refrigerant liquid having a low boiling point is sprayed to the LSIs through nozzles. Since boiling is commenced quickly in the aforesaid boiling type cooling apparatus, the aforesaid overshooting of the temperature of the LSIs can substantially be prevented. However, its simple structure in which the refrigerant liquid having a low boiling point is sprayed to the LSIs will deteriorate the performance of cooling the LSIs because the LSIs disposed in the lower stream of the refrigerant liquid flow are undesirably covered with boiled bubbles if an excessively large quantity of the boiled bubbles are generated in the case where the heating values of the LSIs are excessively large. If a large quantity of the refrigerant liquid is sprayed to the LSIs through the nozzles, an excessively heavy load acts on the LSIs or the junctions of the LSIs, causing a problem to take place in that the reliability of the LSI deteriorates. Hence, the flow velocity and the flow rate of the refrigerant liquid are limited and therefore the cooling performance is undesirably limited. What is worse, discharge of gas-liquid phase refrigerant liquid including the boiled bubbles from the container which accommodates the refrigerant liquid will cause a portion of the boiled bubbles to be retained at an intermediate position of the piping for the refrigerant liquid. As a result, the flow of the refrigerant liquid is made intermittent and unstable.
Therefore, each of the aforesaid conventional structures has been unsatisfactory in terms of overcoming the excessive large heating value of the LSIs and therefore the performance of cooling the LSIs has been insufficient.